1,1-Dichloro-1-fluoroethane is presently under consideration as a replacement for trichlorofluoromethane as a foam blowing agent. It has a substantially lower ozone depletion index than trichlorofluoromethane. Moreover, 1,1-dichloro-1-fluoroethane displays a 10-15% greater blowing efficiency in rigid foam, and improved solubility in aromatic polyester polyol, in comparison to trichloro-fluoromethane.
In the manufacture of 1,1-dichloro-1-fluoroethane, by-products are generated which are not easily separated from the desired product by distillation. Various unsaturated carbon compounds, most notably vinylidene chloride, may be produced. Vinylidene chloride is particularly undesirable, since it is a suspected carcinogen. What is needed is a method for removing unsaturated carbon compounds, particularly vinylidene chloride, which may be generated in the production of 1,1-dichloro-1-fluoroethane.
The photochlorination of trichloroethylene and/or tetrachloroethylene is well-known. British Patent No. 591,780; U.S. Pat. No. 2,440,731; Chemical Abstracts 51:16111h (1957), abstracting Ackerman et al., Bull. Soc. Chim. Belges 66, 325-44 (1957); Dainton et al., Trans. Faraday Soc. 53, 460-7 (1957); Chemical Abstracts 53:13748d (1959), abstracting Adam et al., Bull. Soc. Chim. Belges 65, 942-56 (1956); Chemical Abstracts 53:17646 (1959), abstracting Chiltz et al., Bull. Soc. Chim Belges 68, 5-18 (1959); Dusoleil et al., Trans. Faraday Soc. 57, 2197-2209 (1961); Huybrechts et al., Trans. Faraday Soc. 58, 1128-36 (1962); Huybrechts et al., Trans. Faraday Soc. 61(513,pt 9) (1965); LedakoWicz et al., Int. J. Chem. Kinet. 16(4), 345-52 (1984).
Photochlorination of 1,2-dichloroethylene is described in the following: Anderson, Ind. Eng. Chem. 39, 844-46 (1974); Chemical Abstracts 54:5461c (1960), abstracting German Patent No. 967,011; Ayscough et al., Trans. Faraday Soc. 62(7), 1846-58 (1966).
Cocker et al., Trans. Faraday Soc. 58, 284-94 (1962) discloses the photochlorination of cis- and trans-1,2-dichloroethylene, chloroethylene and trichloroethylene.
The photochlorination of vinylidene chloride, cis-and trans-1,2-dichloroethylene, trichloroethylene and tetrachloroethylene is described in Poutsara et al., J. Am. Chem. Soc. 86(18), 3807-14 (1964) and in Beadle et al., J. Chem. Soc., Faraday Trans. 1, 70(8), 1418-33 (1974). The photochlorination of vinylidene chloride is also disclosed in Ayscough et al., Trans. Faraday Soc. 62(7), 1838-45 (1966).
While the gas phase photochlorination of unsaturated carbon compounds is known, the photochlorination reaction has not been heretofore utilized for converting such compounds, in their liquid mixtures with 1,1-dichloro-1-fluoroethane, to higher boiling compounds in order to facilitate separation from 1,1-dichloro-1-fluoroethane.